Took me awhile to figure out the directions too. What I think they should say is: Take an awl (the picture looks like a screwdriver) and poke holes all around the 2 plastic cutouts and then cut them out with a utility knife. It looks like in the pictures they are telling you to unsrew them.
Also, I had to lengthen the wire that you use to pull the smaller bolt and backing plate thru the tube.
Took me about 15 minutes to complete the whole thing!